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Did you know that Blue Gropers aren’t actually a groper?

Did you know that Blue Gropers aren’t actually a groper?

In southern Australia, the western blue groper is actually the largest carnivorous bony fish species found living on reefs, reaching a length of up to 1.7 metres and a weight of up to 40 kilograms.

The western blue groper is not actually a groper (Family Serranidae) at all, but a member of the wrasse family (Labridae). Wrasses are generally much smaller than gropers and it is thought the large size of the western blue is the reason behind its ‘groper’ name.

The western blue groper is an interesting fish species – which seems to be fascinated with humans. Probably due to its long life span and size, many large specimens of blue groper are very inquisitive when they encounter divers. This behaviour makes them vulnerable to spearfishing, which can consequently lead to localised stock depletion.

Fortunately, in recent years, many dive clubs and individual divers have become aware of the pressure on blue groper stocks and have changed their behaviour from spearfishing for the gropers to simply enjoying a friendly underwater interaction with them.

Blue Groper taken by Johanna Pool

Sex change in the western blue groper is closely associated in a change in colour from green to blue. This occurs when a groper is 30 to 35 years old.

Threat from overfishing

The western blue groper is very vulnerable to heavy fishing, as the species is extremely long-lived, taking many years to reach sexual maturity and even longer to be able to change sex from female to male. Along the west coast – especially in the Perth metropolitan area – the fish is a rare sight nowadays.

Stocks of blue groper along the south-west and south coasts are in much better shape, due to a greater area of suitable habitat, frequent poor weather conditions that can restrict fishing access and a lower number of fishers.

Source: Dept of Fisheries 2011

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